External adjustment of a drive control of a switch

ABSTRACT

A control system to control a conductivity modulated device of a power switching array. The control system comprises a system controller to sense a power event and to output a command signal to adjust a drive characteristic of the conductivity modulated device in response to the sensed power event and a switch controller configured to receive the command signal and to control energy delivery to the load by controlling the turn on and turn off of the conductivity modulated device. The switch controller includes an adjustable drive element to control a rise time and/or fall time of a voltage across the conductivity modulated device and a drive characteristic control to receive the command signal and vary the drive characteristics by control of the adjustable drive element to adjust the rise time and/or fall time of the voltage across the conductivity modulated device in response to the command signal.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a switch controller for asemiconductor switch, and more specifically to a switch controller whichmay be controlled by a user or a system controller.

2. Discussion of the Related Art

Household and industrial appliances such as ventilation fans, coolingsystems, refrigerators, dishwashers, washer/dryer machines, and manyother white products/goods typically utilize electric motors thattransfer energy from an electrical source to a mechanical load.Electrical energy for driving the electric motors is provided through adrive system, which draws electrical energy from an electrical source(e.g., from an ac low frequency source). The electrical energy receivedfrom the electrical source is processed through a power converter, andconverted to a desired form of electrical energy that is supplied to themotor to achieve the desired mechanical output. The desired mechanicaloutput of the motor may be for example the speed of the motor, thetorque, or the position of a motor shaft.

Motors and their related circuitries such as motor drives represent alarge portion of utility network loads. The functionality, efficiency,size, and price of motor drives are challenging and are competitivefactors that suppliers of these products consider. The function of apower converter in a motor drive includes providing the input electricalsignals to the motor such as voltage, current, frequency, and phase fora desired mechanical output load motion (e.g., spin/force) on the motorshaft. The power converter in one example may be an invertertransferring a de input to an ac output of desired voltage, current,frequency, and phase and generally includes one or more switches tocontrol the transfer of energy. Each switch is controlled by a switchcontroller for the power converter.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1 is a functional block diagram of a system with a systemcontroller which adjusts the drive characteristics of a switch inaccordance with embodiments of the present disclosure.

FIG. 2A is a timing diagram of various waveforms of the system of FIG. 1during a switch turn on event, in accordance with embodiments of thepresent disclosure.

FIG. 2B is another timing diagram of various waveforms of the system ofFIG. 1 during a switch turn off event, in accordance with embodiments ofthe present disclosure.

FIG. 3 is a functional block diagram of the system controller and switchcontroller of FIG. 1 illustrating example commands from the systemcontroller to adjust the switch, in accordance with embodiments of thepresent disclosure.

FIG. 4 is a functional block diagram of a switch controller illustratingreceiving commands from a user, in accordance with embodiments of thepresent disclosure.

FIG. 5A is a functional block diagram of a motor driver with a systemcontroller to adjust one or more switches of various half-bridgemodules, in accordance with embodiments of the present disclosure.

FIG. 5B is a functional block diagram of the system controller andhalf-bridge module of FIG. 5A, in accordance with embodiments of thepresent disclosure.

FIG. 6A is a functional block diagram of one example of a powerconverter in a half-bridge configuration with a system controller toadjust one or more switches, in accordance with embodiments of thepresent disclosure.

FIG. 6B is a functional block diagram of another example of a powerconverter in a half-bridge configuration with a system controller toadjust one or more switches, in accordance with embodiments of thepresent disclosure.

FIG. 6C is a functional block diagram of the system controller,interface, and switch controller of FIGS. 6A and 6B, in accordance withembodiments of the present disclosure.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousembodiments of the present invention. Also, common but well-understoodelements that are useful or necessary in a commercially feasibleembodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one having ordinary skill in the art thatthe specific detail need not be employed to practice the presentinvention. In other instances, well-known materials or methods have notbeen described in detail in order to avoid obscuring the presentinvention.

Reference throughout this specification to “one embodiment”, “anembodiment”, “one example” or “an example” means that a particularfeature, structure or characteristic described in connection with theembodiment or example is included in at least one embodiment of thepresent invention. Thus, appearances of the phrases “in one embodiment”,“in an embodiment”, “one example” or “an example” in various placesthroughout this specification are not necessarily all referring to thesame embodiment or example. Furthermore, the particular features,structures or characteristics may be combined in any suitablecombinations and/or subcombinations in one or more embodiments orexamples. Particular features, structures or characteristics may beincluded in an integrated circuit, an electronic circuit, acombinational logic circuit, or other suitable components that providethe described functionality. In addition, it is appreciated that thefigures provided herewith are for explanation purposes to personsordinarily skilled in the art and that the drawings are not necessarilydrawn to scale.

In the context of the present application, when a transistor is in an“off state”, or “off”, the transistor does not substantially conductcurrent. Conversely, when a transistor is in an “on state”, or “on”, thetransistor is able to substantially conduct current. By way of example,in one embodiment, a high-voltage transistor comprises an N-channelmetal-oxide-semiconductor field-effect transistor (NMOS) with thehigh-voltage being supported between the first terminal, a drain, andthe second terminal, a source. In another embodiment, a high-voltagetransistor comprises an insulated-gate bipolar transistor (IGBT) withthe high-voltage being supported between the first terminal, acollector, and the second terminal, an emitter. For purposes of thisdisclosure, “ground” or “ground potential” refers to a reference voltageor potential against which all other voltages or potentials of anelectronic circuit or integrated circuit (IC) are defined or measured.In one example, the transistor or switch may also be referred to as aconductivity modulated device which may be controlled to conduct variousamounts of current.

Inverters with half-bridge switching configurations are commonly usedwith motor drives. Instead of implementing a full bridge switchingconfiguration, utilizing a half-bridge switching circuit with low-sideand high-side control blocks (also referred to as a low-side switchcontroller and high-side switch controller) inside one single package(e.g., a module) allows support for multiphase inverters, such assingle-phase and 3-phase inverters, that provide increased layoutflexibility as well as simplified thermal management for each module.Utilization of a modular half-bridge circuit structure for a motor driveinverter may reduce overall system cost because of a variety of reasons.Each switch of the half-bridge circuit structure is generally controlledby a switch controller which in turn is controlled by a systemcontroller. The switches are controlled by the switch controllers toregulate the energy delivery in response to signals received from thesystem controller and/or a user.

Conductivity modulated devices, such as transistors, maybe be utilizedfor the one or more switches in a power converter, such as an inverter.Typical losses related to conductivity modulated devices are conductionlosses and switching losses (also referred to as crossover losses). Whenthe conductivity modulated device conducts current, the voltage acrossthe conductivity modulated device in response to the current through theconductivity modulated device generates conduction loss. Switchinglosses are generally associated with the losses, which occur while theconductivity modulated device is transitioning between an ON state andan OFF state or vice versa.

In general, a conductivity modulated device takes time to transitionfrom an ON state to an OFF state and vice versa in response to a drivesignal that is provided to a control terminal of the conductivitymodulated device. The control terminal of a field effect transistor(FET), insulated-gate bipolar transistor, or a SiC based transistor isgenerally referred to as the gate terminal. The control terminal of abipolar junction transistor (BIT) is generally referred to as the baseterminal. The time for the conductivity modulated device to transitionfrom an OFF state to an ON state may be referred to as the turn-on timewhereas the time for the conductivity modulated device to transitionfrom an ON state to an OFF state may be referred to as the turn-offtime. Switching/crossover losses occur during this transition time, andthey may be lessened by reducing the duration of the turn-on andturn-off times. In addition, shorter turn-on and turn-off timesgenerally correspond to reduced temperature of the conductivitymodulated device (and therefore the system). However, shorter turn-onand turn-off times also generally correspond with increased system levelelectromagnetic interference (EMI). As such, there is generally atrade-off between EMI, switching losses, and temperature.

The duration of the turn-on and turn-off time of a conductivitymodulated device is related to the characteristics of the drive signalprovided to the control terminal of the conductivity modulated device.It should be appreciated that conductivity modulated devices may bevoltage controlled or current controlled at the gate terminal. Voltagecontrolled conductivity modulated devices typically would be controlledwith a voltage source and a drive resistor (also referred to as a gateresistor) and the drive current for the conductivity modulated device isdetermined by the voltage drop across the control resistor. In otherwords, the value of the voltage source controls the drivecharacteristics of the conductivity modulated device. Current controlledconductivity devices could include a current source and the drivecurrent for the conductivity modulated device is determined by thecharge delivered by the current source. In other words, the value of thecurrent source controls the drive characteristics of the conductivitymodulated device. In one example, the drive signal is a currentcharacterized by its magnitude, direction, and rate of change. Thecharacteristics of the drive current determine the electric charge thatpasses through the control terminal of the conductivity modulateddevice, and it is the electric charge that ultimately modulates theconductivity of the conductivity modulated device. Drive current ofhigher magnitude corresponds to more charge in less time at the controlterminal, resulting in shorter turn-on and/or turn-off time and lowerswitching/crossover losses. There may be conditions in a system, such asa motor drive, where the system controller could determine a need todeliver more power temporarily to a load without exceeding a maximumallowable temperature of the switching devices. The controller canreduce the turn-on and/or turn-off times of the switching devices toprovide the temporary increase in power. Further, the system can beconfigured to tolerate higher electrical noise for the time the higherpower is required. In embodiments of the present invention, thecharacteristics of a driver for a conductivity modulated device may beadjusted by a system controller and/or a user through the switchcontroller and/or a dedicated hardware sensor. The adjusted drive couldincrease or decrease the power delivered to the load within the boundsof other system parameters. In other words, a user and/or a systemcontroller could adjust the drive characteristics of a conductivitymodulated device to meet changing requirements. This could beaccomplished by a switch controller which includes a drivecharacteristic control which can receive a drive characteristic signalrepresentative of one or more drive characteristics of the conductivitymodulated device. Further, in one embodiment, the conductivity modulateddevice may be adjusted in real time by a system controller and/or a userand as such, the drive characteristics of a conductivity modulateddevice may be adjusted on demand to meet changing requirements.

FIG. 1 illustrates a system 100 with a system controller 102 whichadjusts the drive characteristics of a conductivity modulated device106, in accordance with embodiments of the present disclosure. System100 includes a system controller 102 and a power switching army 104. Thepower switching array 104 can include one or more conductivity modulateddevices. As shown, the power switching array 104 includes conductivitymodulated devices 106, 108, 110, and 112. The conductivity modulateddevices 106, 108, 110, and 112 are illustrated as coupled together bydotted lines to emphasize that the power switching array 104 could becoupled in various configurations. For example, the conductivitymodulated devices in the power switching array 104 could berepresentative of transistors of one or more inverters with half-bridgeswitching configurations or other power converter topologies. In anotherexample, the conductivity modulated devices in the power switching array104 could be representative of one or more inverter transistors withfull-bridge switching configurations.

Each conductivity modulated device 106, 108, 110, and 112 is controlledby a switch controller, however for ease of explanation, only the switchcontroller 114 for conductivity modulated device 106 is illustrated. Thevoltage across the conductivity modulated device 106 is shown as voltageV_(DS) 150 (also referred to as drain-source voltage V_(DS) 150) whilethe conducted current of the conductivity modulated device 106 iscurrent I_(D) 148 (also referred to as drain current I_(D) 148). In theexample shown, the conductivity modulated device 106 is a currentcontrolled device. The control current for the conductivity modulateddevice 106 is shown as current I_(G) 146 (also referred to as gatecurrent I_(G) 146). The conductivity modulated device may be atransistor, such as a metal-oxide-semiconductor field-effect transistor(MOSFET), bipolar transistor, injection enhancement gate transistors(IEGT), insulated-gate bipolar transistor (IGBT) and gate turn-offthyristor (GTO). Further, the conductivity modulated device may be basedon silicon (Si), gallium nitride (GaN), or silicon carbide (SiC)semiconductors.

The system controller 102 couples to the switch controller 114 throughinterface 120. In one example, the interface 120 galvanically isolatesthe system controller 102 from the switch controller 114. In anotherexample, the interface 120 does not galvanically isolate the systemcontroller 102 from the switch controller 114. As shown, the systemcontroller 102 receives a sense signal 116 representative of a powerevent. In one example, the power event may be an indication to thesystem controller 102 to provide increased power to a load, such as amotor. In one embodiment, the sensed power event may indicate to thesystem controller 102 to adjust the drive characteristics of theconductivity modulated device 106. In on example, the system controller102 adjusts the drive characteristics of the conductivity modulateddevice 106 by increasing the magnitude of the drive current (e.g. gatecurrent I_(G) 146) of the conductivity modulated device 106. Further, inone embodiment the system controller 102 adjusts the drivecharacteristics of the conductivity modulated device 106 by increasingthe magnitude of the drive current during either the turn-on time, theturn-off time, or both. In one example, the drive current may also bereferred to as the drive strength with greater magnitude of drivecurrents corresponding to greater drive strength. Or in other words, thepower event may indicate to the system controller 102 to decreaseturn-on time and/or turn-off time by increasing the magnitude of thegate current I_(G) 146 to decrease the rise time and/or fall time of thedrain current I_(D) 148 of the conductivity modulated device 106. Insome embodiments, the power event may indicate to the system controller102 to decrease turn-on time and/or turn-off time by increasing themagnitude of the gate current I_(G) 146 to decrease the fall time and/orrise time of the drain-source voltage V_(D)s 150. For example, thesystem controller 102 decreases turn-on time and/or turn-off time bymodulating the value of currents I_(EN) and I_(DIS) of current sources140 and 144. One example of a sensed power event which would increasethe magnitude of the gate current I_(G) 146 could include an outdoor airconditioning fan during startup that may have to overcome possible windblowing conditions. Another example of a sensed power event couldinclude a dishwasher water pump which has to pump a large amount ofwater in case the drain for the dishwasher has unexpectedly flooded. Afurther example of a sensed power event could include a refrigeratorduring initial installation to cool itself to the desired temperature,also known as a cool-down period.

In the embodiment shown in FIG. 1, system controller 102 outputs acommand signal 118 to the switch controller 114. In one example, thecommand signal 118 is outputted in response to the received sense signal116. The command signal 118 is representative of one or more commandsfor the switch controller 114 by the system controller 102 and viceversa. In one example, the communication between the system controller102 and the switch controller 114 is bidirectional. Example commandscommunicated by and/or to the system controller 102 could include a“status inquiry” command in which the system controller 102 pings theswitch controller 114 for the “status” of the switch controller 114,such as the information stored in a status register of the switchcontroller. Another example command communicated with the systemcontroller 102 could include a “fault” command in which the switchcontroller 114 has sensed a fault condition (such as overcurrent,overvoltage, overheating, etc) in the system 100 and communicates thefault to the system controller 102. In general, the switch controller114 responds to a sensed fault by turning off the conductivity modulateddevice 106. A further example command communicated by the systemcontroller 102 could include a “reset” command in which the switchcontroller 114 is restarted or turned on. In embodiments of the presentdisclosure, the system controller 102 communicates an adjustment commandrepresentative of adjusting one or more drive characteristics ofconductivity modulated device 106. An example drive characteristicincludes the magnitude of the gate current I_(G) 146 (e.g. drivestrength) which is related to the rise time and/or fall time of thedrain current I_(D) 148 and the drain-source voltage V_(DS) 150. Themagnitude of the gate current I_(G) 146 may be varied by modulating thevalues of currents I_(EN) and I_(DIS) by current sources 140 and 144.Another example drive characteristic could include the duration whichthe conductivity modulated device 106 is driven by the gate currentI_(G) 146. A further example drive characteristic could include thefrequency which the conductivity modulated device 106 is driven by thegate current I_(G) 146. For example, the gate current I_(G) 146 could bea pulsed signal which may be pulse width modulated (PWM) or pulsefrequency modulated (PPM) in response to the command signal 118. In someembodiments, the command signal 118 could be representative of drivingthe conductivity modulated device 106 at a first magnitude of gatecurrent I_(G) 146 or a second magnitude of gate current I_(G) 146, wherethe second magnitude is greater than the first magnitude. The commandsignal 118 could be a voltage signal or a current signal. In oneexample, the command signal 118 could be representative of a digitalword. Further, the system controller 102 could apply coding to thecommand signal 118.

The interface 120 receives the command signal 118 andinterprets/demodulates the command signal 18 to output the drivecharacteristic signal 128. In embodiments, the drive characteristicsignal 128 is representative of one or more drive characteristics forthe conductivity modulated device 106. The switch controller 114 alsoincludes a drive characteristic control 122 and drive elements 124 and126. As shown, the interface 120 is coupled to and outputs the drivecharacteristic signal 128 to the drive characteristic control 122. Drivecharacteristic control 122 is coupled to drive elements 124, 126 andcontrols drive elements 124, 126 to enable or disable (i.e. turn on orturn off) the conductivity modulated device 106. In embodiments, thedrive characteristic control 122 controls drive elements 124, 126 inresponse to the drive characteristic signal 128. Further, the drivecharacteristic control 122 controls drive elements 124, 126 to enable ordisable (i.e. turn on or turn off) the conductivity modulated device 106with the one or more drive characteristics provided by the drivecharacteristic signal 128. As shown in FIG. 1, the drive characteristiccontrol 122 outputs an enable signal EN 130 and disable signal DIS 134to turn on or turn off the conductivity modulated device 106. In oneexample, the enable signal EN 130 and the disable signal DIS 134 couldbe outputted in response to the command signal 118 from the systemcontroller 102 via the drive characteristic signal 128. In anotherexample, the enable signal EN 130 and the disable signal DIS 134 couldbe outputted in response to one or more signals, separate from commandsignal 118, received by the switch controller 114. Further, the drivecharacteristic control 122 could receive the one or more signals,separate from the command signal 118, and outputs the applicable enablesignal EN 130 or disable signal DIS 134 to turn on or turn off theconductivity modulated device 106

As will be discussed further, in one embodiment the drive characteristiccontrol 122 adjusts the drive strength (e.g. drive current) of theconductivity modulated device 106 by adjusting the current provided bydrive elements 124, 126. As shown, the drive characteristic control 122outputs the enable trim signal 132 and the disable trim signal 136 tothe drive elements 124 and 126, respectively, which adjusts themagnitude of the gate current I_(G) 146 and the subsequent turn-on andturn-off times of the conductivity modulated device 106.

Drive element 124 includes switch 138 and current source 140 withcurrent IN to enable the conductivity modulated device 106. Currentsource 140 is coupled to the conductivity modulated device 106 toprovide current to the control terminal (e.g. gate). Drive element 126includes switch 142 and current source 144 with current I_(DIS) todisable the conductivity modulated device 106. Current source 144 iscoupled to the conductivity modulated device 106 to sink current fromthe control terminal (e.g. gate). In some embodiments, current sources140 and 144 are trimmable current sources in which the magnitudes ofcurrent I_(EN) and current I_(DIS) are responsive to the drivecharacteristic signal 128.

Drive characteristic control 122 is coupled to output an enable signalEN 130 and an enable trim signal 132 to drive element 124. To enable theconductivity modulated device 106 to conduct (i.e. turn on), the drivecharacteristic control 122 outputs the enable signal EN 130 to turn onthe switch 138 and turns off switch 140. The current I_(EN) is sourcedto the control terminal of the conductivity modulated device 106 and themagnitude of the gate current I_(G) 146 of the conductivity modulateddevice 106 is substantially equal to current I_(EN). In one example, theenable signal EN 130 may be a rectangular pulse waveform with varyinglengths of logic high and logic low sections. Logic high sections couldcorrespond to the switch 138 being on while logic low sections couldcorrespond to the switch 138 being off (or vice versa). In oneembodiment, the drive characteristic control 122 outputs the enablesignal EN 130 in response to a signal separate from the command signal118 and the drive characteristic signal 128. Drive characteristiccontrol 122 outputs an enable trim signal 132 to adjust the value of thecurrent I_(EN) and therefore the magnitude of the gate current I_(G)146. In embodiments of the present disclosure enable trim signal 132 isresponsive to the drive characteristic signal 128. The enable trimsignal 132 may be a voltage or current signal, with the magnitude of thecurrent I_(EN) corresponding to the value of the enable trim signal. Inone example of the present disclosure, the enable trim signal 132 cantrim the value of the current I_(EN) to a first current value I₁ or asecond current value I₂, however it should be appreciated that theenable trim signal 132 can trim the value of the current I_(EN) to aplurality of current values. The magnitude of the gate current I_(G) 146controls the fall time of the drain-source voltage VDS 150 and theturn-on time of the conductivity modulated device 106 when switch 138 ison and current source 140 is providing current to the conductivitymodulated device 106 while switch 142 is off. As such, the systemcontroller 102 can adjust the drive characteristics, such as the risetime of the drain current I_(D) 148 and/or the fall time of thedrain-source voltage V_(DS) 150 and the turn-on time, of a conductivitymodulated device 106.

Similarly, the drive characteristic control 122 is configured to outputa disable signal DIS 134 and disable trim signal 136 to drive element126. To disable the conductivity modulated device 106 from conducting(i.e. turn oft), the drive characteristic control 122 outputs thedisable signal DIS 134 to turn on the switch 142 and turns off switch138. The amount of current sinked from the control terminal of theconductivity modulated device 106 is limited by the value of currentIDIS provided by current source 144. In one example, the disable signalDIS 134 is a rectangular pulse waveform with varying lengths of logichigh or logic low sections. Logic high sections could correspond to theswitch 142 being on while logic low sections could correspond to theswitch 142 being off (or vice versa). In one example, the disable signalDIS 134 is substantially the inverse of the enable signal EN 130. In oneembodiment, the drive characteristic control 122 outputs the disablesignal DIS 136 in response to a signal separate from the command signal118 and the drive characteristic signal 128. The drive characteristiccontrol 122 outputs the disable trim signal 136 to adjust the value ofthe current I_(DIS) and therefore the magnitude of the gate currentI_(G) 146. In embodiments of the present disclosure, disable trim signal136 is responsive to the drive characteristic signal 128. The disabletrim signal 136 may be a voltage or current signal, with the magnitudeof the current I_(DIS) corresponding to the value of the disable trimsignal 136. In one example of the present disclosure, the disable trimsignal 136 can trim the value of the current I_(DIS) to a first currentI₁ value or a second current value I₂, however it should be appreciatedthat the disable trim signal 132 can trim the value of the currentI_(D)z to a plurality of current values. The magnitude of the gatecurrent I_(G) 146 controls the fall time of the drain current I_(D) 148and the subsequent turn-off time of the conductivity modulated device106. As such, the system controller 102 can adjust the drivecharacteristics, such as the fall time of the drain current I_(D) 148and the subsequent turn-off time, of a conductivity modulated device106.

In another embodiment, the drive characteristic control 122 may adjustthe drive characteristics for the conductivity modulated device 106 bypulse width modulating or pulse frequency modulating the enable signalEN 130 or the disable signal DIS 134. By pulse width modulating or pulsefrequency modulating the enable signal EN 130 or the disable signal DIS134, the drive characteristic control 122 adjusts the average magnitudeof the gate current I_(G) 146. As such the rise time and/or fall time ofthe drain-source voltage V_(DS) 150 or the drain current I_(D) 148 maybe adjusted and subsequent turn-on and/or turn-off times of theconductivity modulated device 106.

FIG. 2A illustrates an example timing diagram 200 of the enable signalEN 130, gate current I_(G) 146, the drain-source voltage V_(DS) 150 anddrain current I_(D) 148 during a turn-on transition of the conductivitymodulated device 106 of FIG. 1. The example waveforms for the gatecurrent I_(D) 146, drain current I_(D) 148, and drain-source voltageV_(DS) 150 shown in FIG. 2A are straight-line approximations. Further,FIG. 2A illustrates example waveforms for the gate current I_(G) 146,drain current I_(D) 148, and drain-source voltage V_(DS) 150 fordifferent drive strengths. The example waveforms on the right hand sideof the page illustrate providing the conductivity modulated device 106with greater drive current than the examples waveforms on the left handside of the page.

In the example shown, the enable signal EN 130 transitions from logiclow to logic high to turn-on the switch 138 of drive element 124.Similarly, the disable signal (not shown) would transition from logichigh to logic low to turn off switch 142. As such, the conductivitymodulated device 106 is enabled to conduct a drive currant I_(D) 148.

Once the switch 138 is turned on (and switch 142 is turned off) by theenable signal EN 130, the gate current I_(G) 146 increases to themagnitude of current I_(EN) of current source 140. On the left hand sideof the page, current I_(EN) of current source 140 is substantially equalto a first current value I₁.

After the switch 138 is turned on, the dram current I_(D) 148 of theconductivity modulated device 106 increases from zero with slope m₁. Forthe example shown, the drain current I_(D) 148 increases to a peak valueand then decreases to its conduction value. In die embodiment shown inFIG. 2A, the drain-source voltage V_(DS) 150 of the conductivitymodulated device 106 begins to decrease to zero with a slope m₂ once thedrain current I_(D) 148 reaches its peak value. The magnitude of slopesm₁ and m₂ are related to the magnitude of the gate current I_(EN), whichfor the example on the left hand side is substantially equal to thefirst current value I₁ of current source I_(EN) 140. For the exampleshown, the turn-on time 252 begins when the enable signal EN 130transitions to a logic high value and ends when the drain-source voltageV_(DS) 150 is substantially zero and the drain current I_(D) 148 of theconductivity modulated device 160 has reached its conduction value.

On the right hand side of the page, current I_(EN) of current source 140is substantially equal to a second current value I₂. As shown, thesecond current value I₃ is greater than the first current value I₁. Themagnitudes of slopes m₁ (for the drain current I_(D) 148) and m₂ (forthe drain-source voltage V_(DS) 150) are greater as compared to themagnitudes of slopes m₁ and m₂ shown on the left hand side of the page.As such, the rise time of for the dram current I_(D) 148 is shorter (andthe foil time for the dram-source voltage V_(DS) 150 is shorter)resulting in an overall shorter turn-on time 254 for the operation ofthe conductivity modulated device 106 on the right hand side as comparedto the turn-on time 252 shown on the left-hand side of the page. Inother words, varying the value of the current I_(EN) of the currentsource 140 and subsequently the gate current I_(G) 146 of theconductivity modulated device 106 varies the turn-on time of theconductivity modulated device 106. The shaded area under die waveformsfor the drain currant I_(D) 148 and the drain-source voltage V_(DS) 150represents the crossover energy loss during the turn-on of theconductivity modulated device 106. As shown the shaded area on the lefthand side of the page is larger than the right hand side of the page,indicating that the crossover losses for the conductivity modulateddevice 106 on the left hand side of the page is greater than on theright hand side of the page. Shorter turn-on times reduceswitching/crossover losses, which also reduces the amount of dissipatedheat and increases die amount of power delivery by the system 100.However, shorter turn-on times may lead to increase EMI.

FIG. 2B illustrates an example tuning diagram 201 of the disable signalDIS 134, gate current I_(G) 146, die drain-source voltage V_(DS) 150 anddrain current I_(D) 148 during a turn-off transition of the conductivitymodulated device 106 of FIG. 1. Similar to FIG. 2A, the examplewaveforms for the gate current I_(G) 146, drain current I_(D) 148, anddrain-source voltage V_(DS) 150 shown are straight-line approximations.Further, FIG. 2B illustrates the example waveforms for the gate currentI_(G) 146, drain current I_(D) 148, and drain-source voltage V_(DS) 150for different drive strengths. The example waveforms for the gatecurrent I_(G) 146, drain current I_(D) 148, and drain-source voltageV_(DS) 150 on the right hand side of die page has a greater drivecurrent than the example waveforms for gate current I_(G) 146, draincurrent I_(D) 148, and drain-source voltage V_(DS) 150 on die left handside of die page.

The disable signal DIS 134 transitions from logic low to logic high toturn-on die switch 142 of drive element 126. Similarly, the enablesignal (not shown) would transition from logic high to logic low to turnoff switch 138. As such, the conductivity modulated device 106 isdisabled from conducting a drive current I_(D) 148.

Once the switch 142 is turned on (and switch 138 is turned off) by thedisable signal DIS 134, the magnitude of the gate current I_(G) 146 issubstantially die magnitude of current I_(DIS) of current source 144.For the drive element 126 shown in FIG. 1, once the switch 142 is turnedon (and switch 138 is off) the gate current I_(G) 146 is flowing toreturn 127. Due to the direction of current, the gate current I_(G) 146shown in FIG. 2B decreases. Further, die maximum magnitude of the gatecurrent IG 146 is responsive to the magnitude of current I_(DIS) ofcurrent source 144. On the left hand side of the page, current I_(DIS)of current source 144 is substantially equal to a first current valueI₁.

After the switch 142 is turned on, the drain-source voltage V_(DS) 150of the conductivity modulated device 106 begins to increase from zerowith a slope m₂. For the example shown, the drain current I_(D) 148 ofthe conductivity modulated device 106 decreases to zero with slope m₁once the drain-source voltage V_(DS) 150 has reached its peak value. Themagnitude of slopes m₁ and m₂ are related to the magnitude of die gatecurrent I_(G), which for the example on the left hand side issubstantially equal to the first current value I₁ of current sourceI_(DIS) 144. For the example shown, the turn-off time 256 begins whenthe disable signal DIS 134 transitions to a logic high value and endswhen the the drain current I_(D) 148 is substantially zero and thedrain-source voltage V_(DS) 150 of the conductivity modulated device 160has reached its non-conducting value.

On the right hand side of the page, current I_(DIS) of current source144 is substantially equal to a second current value I₂. As shown, thesecond current value b is greater than the first current value I₂. Themagnitudes of slopes m₁ (for the drain current I_(D) 148) and m₂ (forthe drain-source voltage V_(DS) 150) are greater as compared to themagnitudes of slopes m₁ and m₂ shown on the left hand side of die page.As such, the fall time of for fee drain current I_(D) 148 is shorter(and the rise time for fee drain-source voltage V_(DS) 150 is shorter)resulting in an overall shorter turn-off time 258 for the operation offee conductivity modulated device 106 on the right hand side as comparedto the turn-off time 256 shown on the left-hand side of the page. Inother words, varying the value of fee current I_(DIS) of the currentsource 144 and subsequently of fee gate current I_(G) 146 of feeconductivity modulated device 106, the turn-off time of the conductivitymodulated device 106 is shortened. The shaded area under the waveformsfor the dram current I_(D) 148 and the drain-source voltage V_(DS) 150represents the crossover loss during the turn-on of the conductivitymodulated device 106. As shown the shaded area on die left hand side ofthe page is larger than die right band side of the page, indicating thatthe crossover losses for the conductivity modulated device 106 on theleft hand side of the page is greater titan cm the right hand side ofthe page. Shorter turn-off times reduce switching/crossover tosses,which also reduces the amount of dissipated heat and increases theamount of power delivery by the system 100.

FIG. 3 is a functional block diagram of the system controller 102 andswitch controller 114 of FIG. 1 illustrating example command signals 118from the system controller for different commands to adjust theconductivity modulated device 106 and/or the switch controller 114. Itshould be appreciated that the system controller 102, switch controller114 and their respective elements couple and function as describedabove.

As shown, the command signal 118 is a rectangular pulse waveform withhigh and low sections. As will be discussed, the duration of the lowsections corresponds with which command is being transmitted by thesystem controller 102, referred to as active low pulse durationencoding. Under default conditions or steady state conditions, when nocommand is being sent, the command signal 118 is substantially equal tothe high value. In one example, the high value could be substantially 5volts (V). When the system controller 102 sends a command to the switchcontroller 114 via the command signal 118, the command signaltransitions to a low value. In one example, die low value could besubstantially 0V. The duration of the low value section of the commandsignal 118 corresponds to which command is being sent by the systemcontroller 102. Hie example command signal 118 in FIG. 3 is an “activelow” signal in which the duration of the low section corresponds towhich command is being transmitted. However, it should be appreciateddial the command signal 118 may be an “active high” signal in which theduration of the high section corresponds to which command is beingtransmitted.

For example, a first command 360 corresponds to the command signal 118being substantially the low value for a period T. For a second command361, the command signal 118 could be substantially the low value for aperiod 2T. In the example shown, the low section of the second command361 is twice as long as the low section for the first command 360.Similarly for the third command 362 and the fourth command 363. Thecommand signal 118 could be substantially the low value for a period 3Tfor the third command 362, which is three times as long as the lowsection of the first command 360. For the fourth command 363, thecommand signal 118 could be substantially the low value for a period 4T,which is four times as long as the low section of the first command 360.In other words, the duration of each command could be a period T longerthan the duration of the previous command. In one example, the interface120 could include a timer or counter to measure the durations of the lowvalue sections in the command signal 118 to determine which command hasbeen received.

Example commands could include: status inquiry, reset, increase drivecurrent, and decrease drive current. The increase drive current anddecrease drive current commands are adjustment commands/signals toadjust the drive characteristics of the conductivity modulated device106. For the first command 360, the system controller 102 could send a“status inquiry” command in which the system controller 102 pings theswitch controller 114 for the “status” of, of the switch controller 114,such as the information stored in a status register of the switchcontroller

For the second command 361, the system controller 102 could send a“reset” command in which the system controller 102 allows the switchcontroller 114 to be restarted or turned on.

For the third command 362, the system controller 102 could send anadjustment command to “increase drive current” in which the systemcontroller 102 indicates that the switch controller 114 should increaseeither the currant I_(EN) of current source 140 or current I_(DIS) ofcurrent source 144, or both, to decrease the rise time of the draincurrent I_(D) 148 or the fall time of die drain current I_(EN) 148, orboth (i.e. the fall time of the drain-source voltage V_(DS) 150 or therise time of the drain-source voltage V_(DS), 150, or both). Thedecreased rise time or fall time would shorten die turn-on time orturn-off time, respectively, of the conductivity modulated device 106.Under normal operating conditions, die drive characteristic control 122outputs the enable trim signal 132 and the disable trim signal 136 suchthat the current I_(EN) of current source 140 and current I_(DIS) ofcurrent source 144 are substantially equal to the first current value I₁(of FIGS. 2A and 2B). In one example, the system controller 102 outputsthe third command 362 in response to die sense signal 115 indicatingthat there is a power event in the system 100 in which the systemcontroller 102 may want to deliver more power. In response to the thirdcommand 362, the drive characteristic controller 122 could output eitherthe enable trim signal 132 or the disable trim signal (or both) toadjust the value of current I_(EN) of current source 140 or currentI_(DIS) of current source 144 (or both) to the second current value I₂(as drown in FIGS. 2A and 2B) and increasing the drive current of theconductivity modulated device 106.

For the fourth command 363, the system controller 102 could send anadjustment command to “decrease drive current” (or in other words a“return drive current” command) in which the system controller 102indicates that the switch controller 114 should decrease (or return)either the current I_(EN) of current source 140 or current I_(DIS) ofcurrent source 144, or both, to increase the rise time of the draincurrent I_(D) 148 or the fall time of the drain current I_(D) 148, orboth (i.e. increase the fall time of the drain-source voltage V_(DS) 150of the rise time of the drain-source voltage V_(DS) 150, or both). Or inother words, the system controller 102 indicates that the switchcontroller 114 should return the value of current I_(EN) of currentsource 140 or current I_(DIS) of current source 144, or both, to thefirst current value I₁ of FIGS. 2A and 2B. In one example, the sensesignal 115 indicates to the system controller 102 that the increasedpower event in the system 100 has passed. In response to the fourthcommand 363, the drive characteristic controller 122 could output eitherthe enable trim signal 132 or the disable trim signal (or both) toadjust the value of current I_(EN) of current source 140 or currentI_(DIS) of current source 144 (or both) to the first current value I₁ ofFIGS. 2A and 2B and decreases (or returns) the drive current of theconductivity modulated device 106 to its default current value. Althoughfor this example, the commands: status inquiry, reset, increase drivecurrent, and decrease drive current are the first, second, third, andfourth commands 360, 361, 362, and 363, respectively, it should beappreciated that the commands could be in any order.

In some embodiments, the communication between the system controller 102and the switch controller 114 may be bidirectional. For example, theswitch controller 114 may sense a fault condition (such as overcurrent,overvoltage, overheating, etc) in the system 100 and communicates thefault to the system controller 102. The fault communication from theswitch controller 114 may be encoded as a multi-bit word to the systemcontroller 102.

FIG. 4 illustrates the switch controller 114 receiving the commandsignal 118 in response to a toggle 465, in accordance with embodimentsof the present disclosure. In one embodiment, the toggle 465 could be inresponse to a user. In another embodiment, the toggle 465 could be inresponse to a dedicated hardware sensor which senses the power event. Itshould be appreciated that the switch controller 114 and its elementscouple and function as described above. In one example, the switchcontroller 114 may receive commands from both the system controller (notshown) and the toggle 465. In another example, the switch controller 114receives the command signal 118 in response to just the toggle 465.

The user 465 may be a rectangular pulse waveform of logic high and logiclow sections. In one embodiment, die toggle 465 is representative of auser manually selecting from two choices, such as a mechanical switch. Alogic low value for the toggle 465 corresponds to the rise time/falltime of the drain current I_(D) 148 (rise time/fall time of thedrain-source voltage V_(DS) 150) substantially equal to a first value,as for example, the gate current I_(G) 146 substantially equal to thefirst current value I₁ as shown in FIGS. 2A and 2B. A logic high valuefor the toggle 465 could correspond to the rise/fall time of the draincurrent I_(D) 148 (rise time/fall time of the drain-source voltageV_(DS) 150) substantially equal to a second value, as for example, thegate current I_(G) 146 substantially equal to the second current valueI₂ as shown in FIGS. 2A and 2B.

As shown in one embodiment, a transistor 464 is coupled to the interface120 of the switch controller 114 and the return 127. The controlterminal of the transistor 464 is configured to receive the toggle 465.In the embodiment shown, the transistor 464 is a bipolar junctiontransistor (BIT). The base of the transistor 464 is configured toreceive the toggle 465, the emitter of transistor 464 is coupled to thereturn 127 and the collector of the transistor 464 is coupled to theinterface 120. For the embodiment shown, the command signal 118 is avoltage signal and is the collector voltage or the collector-emittervoltage of transistor 464. In operation, when the toggle 465 is low, thetransistor 464 is off and the command, signal 118 is high. As such, ahigh value for the command signal 118 corresponds to the rise time/falltime of the dram current I_(D) 148 (rise time/fall time of thedrain-source voltage V_(DS) 150) substantially equal to the first value.When the toggle 465 is high, the transistor 464 is on and the commandsignal 118 is substantially equal to the return 127 (i.e. low value). Assuch, a low value for the command signal 118 corresponds to the risetime/fall time of the drain current I_(D) 148 (rise time/fall time ofthe drain-source voltage V_(DS) 150) substantially equal to the secondvalue.

FIG. 5A illustrates a multi-phase motor drive system 500 including threehalf-bridge inverter modules 566, 567, and 568, coupled individually toa high-voltage (HV) bus 576 and controlled with a single systemcontroller 102 to drive a motor 569, such as fin example a single-phaseor 3-phase motor. As shown, each half-bridge inverter modules 566, 567,and 568 and the system controller 102 are referenced to return 127.Further, the system controller 102 can adjust the drive characteristicsof one or mote switches of the various half-bridge inverter modules 566,567, and 568, in accordance with the teachings of the presentdisclosure. As drown, each switch is represented by an n-typemetal-oxide-semiconductor field effect transistor (MOSFET) and is aconductivity modulated device as discussed above.

Each half-bridge module 566, 567, 568 are individually coupled to the HVbus 576. Each half-bridge module 566, 567, 568, includes a high sideswitch 570, 571, 572, and a low side switch 573, 574, 575, respectivelycoupled together as a power converter or an inverter in a lull-bridgeconfiguration. Each switch 570, 571, 572, 573.574, and 575 is controlledby its own switch controller (shown further in FIG. 5B) and form a powerswitching array. The half-bridge mid-point terminals HB1, HB2, HB3between each high side and low side switch of their respectivehalf-bridge modules 566, 567, 568, are coupled to the three phaseterminals A, B, and C of the multiphase motor 569. In one example, themotor 569 is a brushless 3-phase DC motor, which may be included in forexample an electric appliance, power tool, fen, or fee like. Inoperation, die half-bridge modules 566, 567, and 568 provides the inputelectrical signals (such as voltage, current, frequency, and phase forthe desired mechanical output load motion) to the motor 569 from theelectrical energy supplied by the HV bus 576. The switching propertiesof switches 570, 570, 571, 572, 573, 574, and 575 are controlled bytheir respective switch controllers to regulate the energy flow to themotor 569. In other words, the switch controllers adjust the output tothe motor 569 to maintain the target operation of the motor 569.

The system controller 102 couples to each half-bridge module 566, 567,and 568 through the communication bus 577. Similar to above, inembodiments die system controller 102 receives a sense signal 116representative of a power event. In one embodiment, the power event maybe an indication to the system controller 102 to adjust one or moredrive characteristics of one or more of switches 570, 570, 571, 572,573, 574, and 575. For embodiments, the system controller adjusts thedrive current of one or more of switches 570, 570, 571, 572, 573, 574,and 575 in response to the sensed power event 116. Or in other words,die power event may indicate to the system controller 102 to decreaseswitch turn-on time and/or turn-off time by increasing the magnitude ofthe gate current I_(G) 146 of one or more of switches 570, 570, 571,572, 573, 574, and 575 to increase the rise time and/or fall time of thedrain current I_(D) 148 of one or more of switches 570, 570, 571, 572,573, 574, and 575. One example of a sensed power event which wouldincrease the magnitude of the gate current I_(G) 146 could include anoutdoor air conditioning fan during startup that may have to overcomepossible wind blowing conditions. Another example of a sensed powerevent could include a dishwasher water pump which has to pump a largeamount of water in case the drain for the dishwasher has unexpectedlyflooded. A further example of a sensed power event could include arefrigerator during initial installation to cool itself to the desiredtemperature.

The system controller 102 is configured to output a command signal toone or more half-bridge modules 566, 567, and 568. In one embodiment,the system controller 102 can send the command signal via thecommunication bus 577. In another embodiment, the system controller 102sends the command signal via a separate connection. The command signal118 could be a voltage signal or a current signal. In one example, thecommand signal 118 could be representative of a digital word. Further,the system controller 102 could apply coding to the command signal 118.As will be further illustrated with respect to FIG. 5B, the systemcontroller 102 outputs a command signal 118 to at least one switchcontroller of one or more half-bridge modules 566, 567, and 568 via thecommunication bus 577. In one embodiment, the command signal isoutputted in response to tire received sense signal 116 and may berepresentative of commands by the system controller 102 for therespective switch controller. Example commands communicated by thesystem controller 102 could include a “status inquiry” command for oneor mote of the half-bridge modules 566, 567, and 568. Another examplecommand communicated by the system controller 102 could include a“fault” command in which the system controller 102 has sensed a faultcondition (such as overcurrent, overvoltage, overheating, etc) in thesystem 100 and communicates the fault to half-bridge modules 566, 567,and 568. In general, die half-bridge modules 566, 567, and 568 respondto the fault command by turning off their respective high-side andlow-side switches.

In embodiments of the present disclosure, the system controller 102communicates a command signal 118, representative of the drivecharacteristics of one or more of the high-side switches 570, 571, 572and low-side switches 573, 574, and 575. An example drive characteristicincludes the magnitude of the gate current I_(G) 146 for the respectiveswitch, which is related to the rise time and/or fall time of the draincurrent I_(D) 148 and drain-to-source voltage 150 for the respectiveswitch. Another example drive characteristic could include the durationwhich one or more of switches 570, 571, 572 573, 574, and 575 is drivenby the gate current I_(G) 146. For example, the command communicated viathe communication bus 577 could be representative of driving one or moreof switches 570, 571, 572 573, 574, and 575 at a first magnitude of gatecurrent I_(G) or a second magnitude of gate current I_(G), where thesecond magnitude is greater than the first magnitude. Although it shouldbe appreciated that the command signal 118 could represent driving oneor more of switches 570, 571, 572 573, 574, and 575 with more titan twomagnitudes of gate current I_(G).

Half-bridge modules 566, 567, and 568 are coupled to a communication bus577, which is also coupled to system controller 102. The communicationbus 577, which in one example is an open collector configuration, iscoupled to a supply voltage V_(UP) through a pull up resistor R_(UP).Further, the communication bus 577 may be in one example, a single-wirecommunication bus. As mentioned above, the communication bus 577 may beutilized by the system controller 102 to communicate commands to one ormore half-bridge modules 566, 567, and 568. In one example, thecommunication bus 577 in normal steady state condition is pulled up tosupply voltage V_(UP), and during any communication can be pulled downby the system controller 102 for sending a command to half-bridgemodules 566, 567, and 568. In one embodiment, the communication bus 577can be pulled down for a detection of a command through a digitalmulti-bit word. In another embodiment, the communication bus 577 can bepulled down to communicate a command as discussed with respect to FIG.3. In some embodiments, the duration which the communication bus 577 ispulled down corresponds with the command sent by the system controller102.

FIG. 5B provides increased detail of the half-bridge modules inaccordance with embodiments of the present disclosure. Specifically,FIG. 5B illustrates the half-bridge module 566, but it should beappreciated that the other half-bridge modules 567, 568, althoughpresent, are not shown in detail. Further the elements included inhalf-bridge modules 567, 568 are similar to what is shown in FIG. 5Bwith regards to half-bridge module 566.

Half-bridge module 566 includes high-side switch 570 and low-side switch537 coupled together in series. The high-side switch 570 and low-sideswitch 537 are exemplified by n-type MOSFETs with their respective bodydiodes. The drain of the high-side switch 570 is coupled to the HV bus576 and the source of the source of low-side switch 573 is coupled toreturn 127. The half-bridge mid-point HB1 is coupled to phase A of motor569.

Half-bridge module 566 further includes switch controllers 114 and 515.Switch controller 114 is coupled to control the low-side switch 573while switch controller 515 is coupled to control the high-side switch570. Both switch controllers 114, 515 include drive characteristiccontrol for their respective switches, as discussed above and inaccordance with embodiments of the present disclosure. The switchcontrollers 114 and 515 can also include interfaces to receive thecommand signal 118, as will be further discussed. Similar to above,switch controllers 114, 515 control the enabling and disabling, alongwith the turn-on time and turn-off time of their respective switches.Further, die switch controllers 114, 515 can adjust the drivecharacteristics of the low-side switch 573 and die high-side switch 570,respectively, in response to the system controller 102.

The system controller 102 is coupled to half-bridge module 566 andswitch controller 114. As shown, die system controller 102 outputs thecommand signal 118 to the switch controller 114. In response to thecommand signal 118 received from the system controller 102, the switchcontroller 114 adjusts the drive characteristics of the low-side switch537. In one embodiment, the interface (not shown) of the switchcontroller 114 receives the command signal 118 and outputs the drivecharacteristic signal to the drive characteristic control of switchcontroller 114. The drive characteristic control then outputs signals tothe drive elements which enable and disable the low-side switch 573. Thesystem controller 102 may send the command signal 118 via thecommunication bus 577 or by another coupling to switch controller 114.

As shown in a dashed line, in some embodiments the system controller 102can optionally be coupled to switch controller 515 to provide thecommand signal 118 rather than providing the command signal 118 via theswitch controller 114. In response to the command signal 118, the switchcontroller 515 adjusts the drive characteristics of the high-side switch570. In one embodiment, the interface (not shown) of the switchcontroller 515 receives the command signal 118 and outputs the drivecharacteristic signal to the drive characteristic control of switchcontroller 515. The drive characteristic control then outputs signals tothe drive elements which enable and disable the high-side switch 570.The system controller 102 may send the command signal 118 by anothercoupling to switch controller 515 or via die communication bus 577.

In another alternative embodiment shown by the dashed line, switchcontroller 114 couples to switch controller 515. The switch controller114 sends either the received command signal 118 or the drivecharacteristic signal 128 to switch controller 515 rather than theswitch controller 515 receiving the command signal 118 from the systemcontroller 102. Communication from the low-side switch controller 114 todie high-side switch controller 515 may be accomplished throughcommunication links between the low-side switch controller 114 and thehigh-side controller 515. For example, die control signals forcontrolling both the high-side switch 570 and low-side switch 573 may bereceived by the low-side switch controller 114 from the systemcontroller 102. The control signal for switching die high-side switch570 may be communicated to the high-side controller 515 from thelow-side switch controller 114 via communication links.

In one embodiment, the low-side switch controller 114 relays the commandsignal 118 received from the system controller 102 to adjust the drivecharacteristics of the high side switch 570, such as the high-side drivecurrent, to the high-side switch controller 515. For this example, thehigh-side switch controller 515 includes the interface (not shown) toreceive the command signal 118 from the low-side switch controller 114mid outputs the drive characteristic signal to the drive characteristiccontrol of switch controller 515. The drive characteristic control thenoutputs signals to drive elements which enable and disable the high-sideswitch 570.

In another embodiment, the low-side switch controller 114 receives thecommand signal 118 to adjust the drive characteristics of the high sideswitch 570, such as the high-side drive current, at an interface (notshown). The interface (not shown) outputs the drive characteristicsignal 128 to adjust the drive characteristics of the high side switch570 and the drive characteristic signal 128 of the low-side switchcontroller 114 is communicated to the high-side switch controller 515.For this example, the high-side switch controller 515 includes its owndrive characteristic control which is coupled to and receives the drivecharacteristic signal 128 of the low-side switch controller 114. Thedrive characteristic control of switch controller 515 then outputssignals to drive elements which enable and disable the high-side switch570.

FIG. 6A illustrates an example power converter 600 with switchcontrollers 114, 615 which include drive characteristic control inaccordance with embodiments of the present disclosure. Switchcontrollers 114, 615 include drive characteristic control which isresponsive to the system controller 102. Further, the system controller102 can adjust the drive characteristics of switches 679, 680, inaccordance with embodiments of the present disclosure. Power converter600 receives an input voltage V_(IN) 602 and is designed to transferelectrical energy form an input to a load 682 through an energy transferelement L1 681 by controlling the switching of power switches 679, 680.In various implementations, the power converter 600 can control thevoltage, current, or power levels of the energy output to the load 682.In the example shown in FIG. 6A, the energy transfer element L1 681 andtwo power switches 679, 680 are coupled together in a half-bridgeconfiguration, however other topologies can be used. The power switches679, 680 form a power switching array. Switch controller 114 may bereferred to as a low-side switch controller while switch controller 615may be referred to as a high-side switch controller.

In the example shown, power switches 679, 680 are IGBTs. However,examples of the present invention can also be used in combination withother power switch technologies. For example, metal-oxide-semiconductorfield-effect transistors (MOSFETs), bipolar transistors, injectionenhancement gate transistors (IEGTs) and gate turn-off thyristors (GTOs)can be used. In addition, power converter 600 can be used with powerswitches which are based on gallium nitride (GaN) semiconductors orsilicon carbide (SiC) semiconductors.

System controller 102 is coupled to receive system inputs 699, sensesignal 116 and provides the command signal 118. The system controller102 determines whether the switch controllers 114, 615 should turn oncar turn off the power switches 679, 680 based on system inputs 699.Example system inputs 699 include pulse width modulated (PWM) signal fora general purpose motor drive, a turn-on and turn-off sequence of amulti-level power converter, or a system fault turn-off request. Thesense signal 116 is also a system input and in one embodiment isrepresentative of a power event. In one embodiment, the power event maybe an indication to the system controller 102 to adjust the drivecharacteristic of either power switch 679, 680 or both. In one exampleof adjusting the drive characteristic of either power switch 679, 680,the power event may be an indication to increase the drive current ofeither power switch 679, 680 or both. Or in other words, the power eventmay indicate to the system controller 102 to decrease turn-on timeand/or turn-off time by increasing the magnitude of the control currentfor either power switch 679, 680 or both to increase the rise timeand/or fall time of die current conducted by either power switch 679,680 or both.

In the illustrated example, system controller 102 outputs a commandsignal 118 representative of one or mote commands to the interface 120of switch controllers 114, 615. Example commands include enabling ordisabling power switches 679, 680, reset, fault notification, and adjustthe drive current (i.e. rise time and/or fall time of conducted current)of power switches 679, 680. The command signal 118 could be a voltagesignal or a current signal. In one example, the command signal 118 couldbe representative of an N-bit digital word. Further, the systemcontroller 102 could apply coding to the command signal 118. In oneexample, the communication between the system controller 102 and theinterface 120 may be bidirectional.

Interface 120 is coupled to the system controller 102 and receives thecommand signal 118. FIG. 6A illustrates a single interface 120 for boththe switch controllers 114, 615. However, it should be appreciated thateach switch controller 114, 615 may have its own interface and as suchthe system controller 102 would output the command signal 118 to bothinterfaces. The interface 120 and the system controller 102 are bothreferenced to a primary reference potential 683 while the switchcontroller 114 is referenced to a secondary reference potential 684 andthe switch controller 615 is referenced to a secondary referencepotential 685. Secondary reference potentials 684, 685 are differentpotentials. In one example, reference potential 685 is coupled to thehalf-bridge point between the high-side switch 679 and the low-sideswitch 680 while reference potential 684 is coupled to the emitter oflow-side switch 680. The switch controllers 114, 615 are galvanicallyisolated from the interface 120 by isolated communication links 678. Theisolated communication links 678 may be implemented as an inductivecoupling, such as a signal transformer or coupled inductor, opticalcoupling, or capacitive coupling. Further, the switch controllers 114,615 may bidirectionally communicate with the interface 120 via thecommunication links 678.

Interface 120 interprets the command signal 118 sent by the systemcontroller 102 and sends the drive characteristic signal to switchcontrollers 114, 615 to drive the power switches 679, 680 and further,to adjust the drive current of power switches 679, 680. The switchcontrollers 114, 615 receive their respective drive characteristicsignals and generate drive signals to control the power switches 670,680. As discussed above, the switch controllers 114, 615 include drivecharacteristic control circuits and enable and disable drive elements tocontrol die drive current (i.e. drive strength) of power switches 680,679. As such, the system controller 102 adjusts the drive strength ofpower switches 680, 679.

FIG. 6B illustrates another example of a power converter 601 in ahalf-bridge configuration with a system controller 102 to adjust thedrive characteristics, such as for example the drive current, of powerswitches 679, 680. It should be appreciated that die power converter 601shares many similarities with the power converter 600 shown in FIG. 6B.At least one difference however, is the interface 120 couples to switchcontroller 114 through isolation interface 678 and does not couple tothe switch controller 615. For the example shown in FIG. 6B, interface120 interprets the command signal 118 and outputs tike drivecharacteristic signal 128 to the switch controller 114. The switchcontroller 114 sends the drive characteristic signal 128 to switchcontroller 615 rather than the switch controller 815 receiving the drivecharacteristic signal from interface 120. Communication from thelow-side switch controller 114 to die high-side switch controller 615may be accomplished through communication links between the low-sideswitch controller 114 and the high-side controller 615. For thisexample, the high-side switch controller 615 includes its own drivecharacteristic control which is coupled to and receives the drivecharacteristic signal 128 of the low-side switch controller 114. Thedrive characteristic control of switch controller 615 then outputssignals to drive elements which enable and disable the high-side switch679.

FIG. 6C illustrates an example isolated communication link 678. Forsimplicity, only die isolated communication link 678 between interface120 and switch controller 114 is shown. The interface 120 and the systemcontroller 102 are both referenced to a primary reference potential 683while the switch controller 114 is referenced to a secondary referencepotential 684. The switch controller 114 is galvanically isolated fromthe interface 120 by isolated communication links 678. The isolatedcommunication links 678 illustrated to a signal transformer with aprimary winding 687 and a secondary winding 689. The interface 120 iscoupled to the primary winding 687 and outputs the drive characteristicsignal 128. The switch controller 114 is coupled to the secondarywinding 689 and receives the drive characteristic signal 128 multipliedby the turns ratio of the primary and secondary windings 687, 689.

The above description of illustrated examples of the present invention,including what is described in the Abstract, are not intended to beexhaustive or to be limitation to the precise forms disclosed. Whilespecific embodiments of, and examples for, the invention are describedherein for illustrative purposes, various equivalent modifications arepossible without departing from the broader spirit and scope of thepresent invention. Indeed, it is appreciated that the specific examplevoltages, currents, frequencies, power range values, times, etc., areprovided for explanation purposes and that other values may also beemployed in other embodiments and examples in accordance with theteachings of the present invention.

Although the present invention is defined in the claims, it should beunderstood that the present invention can alternatively be defined inaccordance with the following examples:

Example 1

A control system configured to control a conductivity modulated deviceof a power switching array that is configured to control energy deliveryto a load, comprising a system controller configured to sense a powerevent in the control system and to output a command signal to adjust adrive characteristic of the conductivity modulated device in response tothe sensed power event; and a switch controller coupled to the systemcontroller and configured to receive the command signal, the switchcontroller further configured to control energy delivery to the load bycontrolling the turn on and turn off of the conductivity modulateddevice, wherein the switch controller comprises an adjustable driveelement configured to control a rise time and/or a fall time of avoltage across the conductivity modulated device; and a drivecharacteristic control configured to receive the command signal and varydie drive characteristic of the conductivity modulated device, the drivecharacteristic control further configured to vary the adjustable driveelement to adjust the rise time and/or the fell time of the voltageacross the conductivity modulated device in response to the commandsignal generated by die system controller.

Example 2

The control system of example 1, the drive characteristic controlconfigured to adjust a rise time and/or a fall time of a currentconducted by the conductivity modulated device.

Example 3

The control system of examples 1 or 2, wherein the adjustable driveelement comprises a switch coupled to the drive characteristic control,the switch configured to be turned on or off to enable or disable theconduction of current by the conductivity modulated device; and atrimmable current source coupled to the drive characteristic control andcoupled in series with the switch, the drive characteristic controlbeing further configured to control a current provided by fee trimmablecurrent source in response to fee command signal to vary the rise timeand/or the fall time of the voltage across fee conductivity modulateddevice.

Example 4

The control system of any one of examples 1 to 3, fee drivecharacteristic control further configured to control the currentprovided by the trimmable current source to vary a rise time and/or afall time of fee current conducted by fee conductivity modulated device.

Example 5

The control system of any one of examples 1 to 4, wherein the drivecharacteristic control is further configured to control a magnitude ofthe current provided by fee trimmable current source.

Example 6

The control system of any one of examples 1 to 5, wherein the drivecharacteristic control is further configured to control a duration ofthe current provided by the trimmable current source.

Example 7

The control system of any one of examples 1 to 6, wherein the drivecharacteristic control is further configured to control a frequency ofthe current provided by the trimmable current source.

Example 8

The control system of any one of examples 1 to 7, wherein the switchcontroller further comprises an interface coupled to the systemcontroller and configured to receive a command signal, the interfacefurther configured to interpret the command signal and output a drivecharacteristic signal to the drive characteristic control to adjust therise time and/or fall time of conductivity modulated device.

Example 9

The control system of any one of examples 1 to 8, wherein the interfaceis galvanically isolated from the drive characteristic control.

Example 10

The control system of any one of examples 1 to 9, wherein the controlsystem controls energy delivery to a motor.

Example 11

The control system of any one of examples 1 to 10, wherein theconductivity modulated device is a transistor.

Example 12

The control system of any one of examples 1 to 11, wherein the commandsignal is a rectangular pulse waveform of logic high and logic lowsections, wherein a duration of the logic low section corresponds to acommand of the command signal.

Example 13

The control system of any one of examples 1 to 12, wherein the systemcontroller is configured to output die command signal to adjust theconductivity modulated device on demand.

Example 14

A control system configured to control a conductivity modulated devicewhich is configured to control energy delivery to a load, comprising asystem controller configured to sense a power event in the controlsystem and to assert a command signal in response to the sensed powerevent; and a switch controller coupled to the system controller andconfigured to receive the command signal, the switch controller furtherconfigured to control the turn on and the turn off of the conductivitymodulated device to control the energy delivery to the load by variationof a rise time, a fall time, or both of a voltage across theconductivity modulated device in response to a first command in thecommand signal, wherein the switch controller is configured to not varythe rise time, the fall time, or both in response to a second command inthe command signal.

Example 15

The control system of example 14, wherein the switch controller furthercomprises: an adjustable drive element configured to control the riselime, the fall time or both of the voltage across the conductivitymodulated device; an interface coupled to the system controller andconfigured to receive the command signal, wherein the interface isconfigured to interpret the command signal and output a drivecharacteristic signal; and a drive characteristic control configured toreceive the drive characteristic signal and vary die adjustable driveelement to adjust the rise time, the fall time, or both of the voltageacross the conductivity modulated device from a default value inresponse to the first command in the command signal, the drivecharacteristic control is configured to not vary the rise time, the falltime, or both from the default value in response to the second commandin the command signal.

Example 16

The control system of example 14 or 15, wherein the adjustable driveelement further comprises: a switch coupled to the drive characteristiccontrol, wherein the drive characteristic control is configured to turnthe switch ON or OFF to enable or disable the conduction of theconductivity modulated device; and a trimmable current source coupled tothe drive characteristic control and coupled in series with the switch,wherein the drive characteristic control is configured to control amagnitude of current provided by the trimmable current source iscontrolled by die drive characteristic control in response to the drivecharacteristic signal to vary the rise time, the fall time, or both ofdie voltage across the conductivity modulated device.

Example 17

The control system of any one of examples 14 to 16, wherein themagnitude of current provided by the trimmable current source increasesin response to the first command.

Example 18

A switch controller configured to control energy delivery to a load bycontrolling the turn on and turn off of a conductivity modulated device,the switch controller comprising: a drive characteristic controlconfigured to receive drive characteristics from a command signal,wherein die command signal is provided to actively adjust a drivecurrent of the conductivity modulated device; and a first drive elementcoupled to the drive characteristic control comprising a first switchcoupled to the drive characteristic control and configured to be turnedon or off to transition the conductivity modulated device from a firststate to a second state; and a first trimmable current source coupled tothe drive characteristic control and coupled in series with the firstswitch, the first trimmable current source configured to provide currentfor die conductivity modulated device to transition the conductivitymodulated device from the first state to the second state at a firstrate in response to a first command of die command signal and to providecurrent for die conductivity modulated device to transition dieconductivity modulated device from the first state to the second slateat a second rate in response to a second command of the command signal.

Example 19

The switch controller of example 18, further comprising a second driveelement coupled to the drive characteristic control, wherein die seconddrive element comprises: a second switch coupled to die drivecharacteristic control and configured to be turned on or off totransition the conductivity modulated device from the second state tothe first state; and a second trimmable current source coupled to thedrive characteristic control and coupled in series with the secondswitch, die second trimmable current source is configured to providecurrent for the conductivity modulated device to transition dieconductivity modulated device from the second state to the first stateat die first rate in response to the first command of the command signaland to provide current for the conductivity modulated device totransition the conductivity modulated device from the second state tothe first state at the second rate in response to the second command ofthe command signal.

Example 20

The switch controller of example 18 or 19, wherein the command signal isreceived from a system controller.

Example 21

The switch controller of any one of examples 18 to 20, wherein thecommand signal is received from a user toggle.

Example 22

The switch controller of any one of examples 18 to 21, wherein foecommand signal is received from a sensor.

The invention claimed is:
 1. A control system configured to control aconductivity modulated device of a power switching array and configuredto control energy delivery to a load, comprising: a system controllerconfigured to sense a power event in the control system and to output acommand signal to adjust a drive characteristic of the conductivitymodulated device in response to the sensed power event; and a switchcontroller coupled to die system controller and configured to receivethe command signal, the switch controller further configured to controlenergy delivery to the load by controlling the turn on and turn off ofthe conductivity modulated device, wherein the switch controllercomprises: an adjustable drive element configured to control a risetime, a fall time, or both of a voltage across the conductivitymodulated device; and a drive characteristic control configured toreceive the command signal and vary the drive characteristic of dieconductivity modulated device, the drive characteristic control furtherconfigured to vary the adjustable drive element to adjust the rise timethe fall time, or both of the voltage across the conductivity modulateddevice in response to the command signal generated by the systemcontroller.
 2. The control system of claim 1, die drive characteristiccontrol configured to adjust a rise time, a fall time, or both of acurrent conducted by the conductivity modulated device.
 3. The controlsystem of claim 1, wherein the adjustable drive element comprises: aswitch coupled to the drive characteristic control, the switchconfigured to be turned on or off to enable or disable the conduction ofcurrent by the conductivity modulated device; and a trimmable currentsource coupled to the drive characteristic control and coupled in serieswith the switch, the drive characteristic control being furtherconfigured to control a current provided by the trimmable current sourcein response to the command signal to vary the rise time, the fall time,or both of the voltage across fee conductivity modulated device.
 4. Thecontrol system of claim 3, the drive characteristic control furtherconfigured to control the current provided by the trimmable currentsource to vary a rise time, a fall time, or both of the currentconducted by the conductivity modulated device.
 5. The control system ofclaim 3, wherein the drive characteristic control is further configuredto control a magnitude of the current provided by the trimmable currentsource.
 6. The control system of claim 3, wherein the drivecharacteristic control is further configured to control a duration ofthe current provided by the trimmable current source.
 7. The controlsystem of claim 3, wherein the drive characteristic control is furtherconfigured to control a frequency of tire current provided by thetrimmable current source.
 8. The control system of claim 1, wherein theswitch controller further comprises: an interface coupled to the systemcontroller and configured to receive a command signal, the interfacefurther configured to interpret the command signal and output a drivecharacteristic signal to the drive characteristic control to adjust therise time, the fall time, or both of the voltage across the conductivitymodulated device.
 9. The control system of claim 8, wherein theinterface is galvanically isolated from the drive characteristiccontrol.
 10. The control system of claim 1, wherein the control systemcontrols energy delivery to a motor.
 11. The control system of claim 1,wherein die conductivity modulated device is a transistor.
 12. Thecontrol system of claim 1, wherein die command signal is a rectangularpulse waveform of first logic state and second logic state sections,wherein a duration of the logic low section corresponds to a command ofthe command signal.
 13. The control system of claim 1, wherein thesystem controller is further configured to output the command signal toadjust the conductivity modulated device on demand.
 14. A control systemconfigured to control a conductivity modulated device which isconfigured to control energy delivery to a load, comprising: a systemcontroller configured to sense a power event in the control system andto assert a command signal in response to the sensed power event; and aswitch controller coupled to die system controller and configured toreceive the command signal, the switch controller further configured tocontrol the turn on and the turn off of the conductivity modulateddevice to control the energy delivery to the load by variation of a risetime, a fall time, or both of a voltage across the conductivitymodulated de vice in response to a first command in die command signal,wherein the switch controller is configured to not vary the rise time,the fall time, or both in response to a second command in the commandsignal.
 15. The control system of claim 14, wherein the switchcontroller further comprises: an adjustable drive element configured tocontrol die rise time, the fall time car both of the voltage across theconductivity modulated device; an interface coupled to die systemcontroller and configured to receive the command signal, wherein theinterface is configured to interpret die command signal and output adrive characteristic signal; and a drive characteristic controlconfigured to receive the drive characteristic signal and vary theadjustable drive element to adjust the rise time, the fall time, or bothof the voltage across the conductivity modulated device from a defaultvalue in response to the first command in the command signal, the drivecharacteristic control further configured to not vary the rise time, thefall time, or both from the default value in response to the secondcommand in the command signal.
 16. The control system of claim 15,wherein fee adjustable drive element further comprises: a switch coupledto the drive characteristic control, wherein the drive characteristiccontrol is configured to turn the switch ON or OFF to enable or disablethe conduction of the conductivity modulated device; and a trimmablecurrent source coupled to fee drive characteristic control and coupledin series wife fee switch, wherein the drive characteristic control isconfigured to control a magnitude of current provided by the trimmablecurrent source in response to the drive characteristic signal to varyfee rise time, the fall time, or both of fee voltage across theconductivity modulated device.
 17. The control system of claim 16,wherein the magnitude of current provided by fee trimmable currentsource increases in response to the first command.
 18. A switchcontroller configured to control energy delivery to a load bycontrolling the turn on and turn off of a conductivity modulated device,the switch controller comprising: a drive characteristic controlconfigured to receive drive characteristics from a command signal,wherein the command signal is provided to actively adjust a drivecurrent of the conductivity modulated device; and a first drive elementcoupled to the drive characteristic control comprising: a first switchcoupled to the drive characteristic control and configured to be turnedon or off to transition the conductivity modulated device from a firststate to a second state; and a first trimmable current source coupled tothe drive characteristic control and coupled in series with the firstswitch, the first trimmable current source configured to provide currentfor the conductivity modulated device to transition the conductivitymodulated device from the first state to the second state at a firstrate in response to a first command of the command signal and to providecurrent for the conductivity modulated device to transition theconductivity modulated device from the first state to the second stateat a second rate in response to a second command of the command signal.19. The switch controller of claim 18, further comprising a: a seconddrive element coupled to the drive characteristic control, wherein thesecond drive element comprises: a second switch coupled to the drivecharacteristic control and configured to be turned on or off totransition the conductivity modulated device from the second state tothe first state; and a second trimmable current source coupled to thedrive characteristic control and coupled in series with the secondswitch, the second trimmable current source is configured to providecurrent for the conductivity modulated device to transition theconductivity modulated device from the second state to the first stateat the first rate in response to the first command of the command signaland to provide current for the conductivity modulated device totransition the conductivity modulated device from the second state tothe first state at the second rate in response to the second command ofthe command signal.
 20. The switch controller of claim 18, wherein thecommand signal is received from a system controller.
 21. The switchcontroller of claim 18, wherein die command signal is received from auser toggle.
 22. The switch controller of claim 18, wherein the commandsignal is received from a sensor.
 23. A control system configured tocontrol a transistor which is configured to control energy delivery to aload, comprising: a system controller configured to sense a power eventin the control system and to assert a command signal in response to thesensed power event; and a switch controller coupled to the systemcontroller and configured to receive the command signal, the switchcontroller further configured to control the turn on and the turn off ofthe transistor to control the energy delivery to the load and to vary adrive strength of the transistor in response to a first command in thecommand signal, wherein the switch controller is configured to not varythe drive strength of the transistor in response to a second command inthe command signal.
 24. The control system of claim 23, wherein theswitch controller further comprises: an adjustable drive elementconfigured to control a rise time, a fall time or both of a currentconducted by the transistor; an interface coupled to the systemcontroller and configured to receive the command signal, wherein theinterface is configured to interpret the command signal and output adrive characteristic signal; and a drive characteristic controlconfigured to receive the drive characteristic signal and vary theadjustable drive element to adjust the rise time, the fall time, or bothof the current conducted by the transistor from a default value inresponse to the first command in the command signal, the drivecharacteristic control configured to not vary the rise time, the falltime, or both from the default value in response to the second commandin the command signal.
 25. The control system of claim 24 wherein theadjustable drive element further comprises: a switch coupled to thedrive characteristic control, wherein the drive characteristic controlis configured to turn the switch ON or OFF to enable or disable theconduction of the transistor; and a trimmable current source coupled tothe drive characteristic control and coupled in series with the switch,wherein the drive characteristic control is configured to control amagnitude of current provided by the trimmable current source inresponse to the drive characteristic signal.
 26. The control system ofclaim 25 wherein the magnitude of current provided by the trimmablecurrent source increases in response to the first command.
 27. Thecontrol system of claim 24, wherein the switch controller furthercomprises: an adjustable drive element configured to control the risetime, the fall time or both of a voltage across the transistor; aninterface coupled to the system controller and configured to receive thecommand signal, wherein the interface is configured to interpret thecommand signal and output a drive characteristic signal; and a drivecharacteristic control configured to receive the drive characteristicsignal and vary the adjustable drive element to adjust the rise time,the fall time, or both of the voltage across the transistor from adefault value in response to the first command in the command signal,the drive characteristic control configured to not vary the rise time,the fall time, or both from the default value in response to the secondcommand in the command signal.